A number of in-shoe systems exist for monitoring contact forces and pressures in various environments, for example clinical environments. A common method uses force sensitive resistors positioned around a foot/shoe interface although accuracy and reliability of the resistive sensors is limited. A relatively slow response time of the force sensitive resistor sensors in systems precludes use in real-time control applications. In addition, the sensors are not sufficiently robust or reliable to be used in demanding environments. Load cells can supply multi-axis force data and are more accurate and reliable, however are too large and heavy to allow multi-site data collection, within the limited form factor of a shoe.
In one example of an in-shoe sensor application, a lower-extremity exoskeleton robot can be used to increase a person's payload capacity and endurance. The Berkeley Lower-Extremity Exoskeleton (BLEEX) is an example of such a device. The BLEEX system senses the wearer's intended movements and generates additional force. The system is self-powered, robust and durable. Ground contact pressure information can be supplied to the robot's control system enabling more reliable control in rugged environments. For example, a robot that senses the phase of a wearer's gait can form a more intelligent response. If the robot simply amplifies all sensed forces, events such as hitting a toe on a rock could be worsened by the exoskeleton control system.